RENEE MONTAGNE, HOST:
Many people use artificial sweeteners as a substitute for sugar. Now, more are using a substitute for artificial sweeteners. A natural sweetener that's gaining popularity is called Stevia.
STEVE INSKEEP, HOST:
MONTAGNE: That's Stevia.
INSKEEP: I'm right here.
MONTAGNE: Steve, the name of the sweetener is Stevia.
INSKEEP: Ah, yes. Please, go ahead.
MONTAGNE: The powder - in little, green packets - has no calories and a growing number of fans, as NPR's Dan Charles reports.
DAN CHARLES, BYLINE: Those green packets of Stevia have been around for a while. But until four years ago, American food companies weren't allowed to use it in soft drinks or cakes. Then, in 2008, the Food and Drug Administration said, OK, Stevia is safe. Europe followed and now, there's a kind of Stevia gold rush under way.
GROVER WICKERSHAM: It could be the biggest non-sugar sweetener - and that's really big.
CHARLES: Grover Wickersham is right in the middle of it. I met Wickersham at the Village Pub in Woodside, California. It's a Silicon Valley kind of place, a venture capital hangout. Wickersham has one foot in this big-money part of California; he's a deal-making securities lawyer. But the other foot is in the farmland of California's Central Valley.
He's the son of a rancher and now, he's chairman of S&W Seed Company, which grows and sells alfalfa seed. When Wickersham heard about stevia, the Silicon Valley side of him said wow, that's a hot new business: an all-natural sugar substitute. And the farming side said hey, this comes from a plant.
WICKERSHAM: You grow it in the soil.
CHARLES: Right now, Asian companies dominate the stevia business. The biggest market is in Japan, and Chinese farmers grow most of it by hand. Wickersham thought, maybe we can do better.
WICKERSHAM: Because, you know, California's famous for being able to grow pretty much anything as well or better than any other place in the world. So we may not be able to compete with making all the things that are made in China but actually, one area where California does compete really effectively is agriculture.
CHARLES: Today, Wickersham's company has thousands of little stevia seedlings growing in a cavernous, rented greenhouse south of Salinas. Koren Sihota is in charge of the project.
KOREN SIHOTA: These are all stevia plants. This is just the beginning of our spring planting. We're making more and more plants.
CHARLES: How many do you want to make?
CHARLES: A full-grown stevia plant is a leafy bush, about knee-high. There's a man at the greenhouse today who has a longer history with stevia than almost anyone else in the United States: Clint Shock, a researcher at Oregon State University. Shock first saw stevia 40 years ago in Paraguay. Some farmers there were growing it in their gardens.
CLINT SHOCK: And they gave me some plants. They also explained where it grew in nature.
CHARLES: So Shock went to the places where stevia grew wild.
SHOCK: And we got a whole truckload of little plants, and started a plantation.
CHARLES: That venture flopped - marketing problems, Shock says. But now he has another chance, working with Koren Sihota and his team. They're trying to turn this wild plant into an industrial-scale crop at Silicon Valley speed - figuring out how to plant and harvest it mechanically, trying to breed new varieties of stevia, turning the plant into a better biological sweetness factory.
SHOCK: Ideally, what we would want is very little leaf, with 10 times the sweetness - one, big plant that's got a lot of sweetness, and we harvest it once.
CHARLES: The harvest - dried leaves that look a little bit like hay - goes to a big stevia processor called Pure Circle. It's up to Pure Circle to extract the sweet compounds from these leaves and make something that tastes just like sugar - which, it turns out, is quite a challenge.
Paul Breslin, a psychologist of taste at Rutgers University and also, the Monell Center in Philadelphia, says people don't really think about how sugar tastes -how quickly they sense sweetness, and how quickly it fades.
PAUL BRESLIN: But if you give them something that differs from that, like something that just lingers way too long, they'll notice that immediately and they'll say, it really lingers in my mouth.
CHARLES: Let's do a little taste test with Stevia, Breslin says. We rip open two, little, green packets and mix the sweet powder into cups of hot water. Then we take five sips, one right after the other, to see if each sip tastes the same.
BRESLIN: That's one - sweet.
CHARLES: But by the fifth sip, that sweetness somehow disappears. That doesn't happen with sugar, Breslin says. But it does with all the zero-calorie sweeteners, including Stevia. Now the big stevia processor, Pure Circle, says they're working on this.
Sidd Purkayastha, the company's vice president for global technical development, says the interesting thing is, stevia leaves actually contain a whole family of different sweet molecules, called steviol glycosides. So you can create different mixtures tweaking the taste.
SIDD PURKAYASTHA: What we found - that as we bring together different steviol glycoside molecules, they start performing better, in many cases, and more like sugar.
CHARLES: Maybe the perfect combination, he says, is a mixture of Stevia and regular sugar. You'd have some calories, but a lot fewer. You'd have the sweetness that people crave, and you could still call it all-natural.
Dan Charles, NPR News.